The invention relates to an electrical device, particularly a television, having a power supply unit that has a voltage converter and an interference suppression capacitor and having a control unit disposed on the primary side that has its own power supply circuit connected directly to the mains voltage and which can be controlled through an external signal, wherein the electrical device has an energy saving mode and the control unit is designed such that when the electrical device enters the energy saving mode, the electrical energy on the secondary side of the power supply unit is switched off.
Electrical devices such as televisions, DVD players, air conditioners and a variety of other devices are usually equipped with a remote control with which the device can be operated and switched off.
To enable the devices to be switched on again using the remote control, the devices remain in a state of operational readiness (stand-by mode) after being switched off.
However, this requires that at least the receiver for the remote control signals and the associated circuit are still supplied with power. In the prior art, the stand-by mode is mainly realized in that the device disconnects the circuit parts that are not needed from the power supply. The power supply unit of the device, however, still remains connected to the mains voltage.
Thus known electrical devices require at least 100 mW in stand-by mode. Mostly, however, power consumption is considerably higher and in worse cases can be as high as several watts. If this kind of device is operated 24 hours a day over 365 days in the year, the electricity costs are not inconsiderable and a not inconsiderable amount of energy has to be permanently available to supply the stand-by mode of a large number of these devices with power.
Hence in the prior art, many attempts have been made to reduce the power consumption of electrical devices in stand-by mode.
A known system, for example, uses relays that disconnect the primary power supply between the mains connection and the power supply unit. This kind of device can be switched off using the remote control. Since the relays interrupt the entire power supply, there is no energy at all available for a remote control receiver and the device has to be manually switched on again using a switch on the device.
Another known system also uses relays to disconnect the power supply from the mains. A remote control receiver, through which the device can be switched on, is supplied with power through a capacitor (Gold Cap) that is charged during normal operation. However, the Gold Cap has only limited capacitance which is not sufficient for bridging long switch-off periods.
Other systems draw power for the signal receiver from external sources, such as from a mains cable or a signal cable from an external energy source, such as a computer or DVD player.
From WO 2010/003785 A2, an electrical device is known that has a stand-by mode having considerably lower power consumption. This is achieved in that the power supply on the secondary side is switched off and on the primary side only a signal receiver and a control unit are supplied with power directly from the main grid. The control unit switches the energy supply on the secondary side of the power supply on or off according to the signals the control unit receives. This makes it possible to reduce power consumption in the stand-by mode even more than in the prior art.